Drill/injector combination for plug fertilization at lift

ABSTRACT

A drill/injector combination is provided to inject plants that are grown in containers such as blocks at lift with plant growth modulators. The drill/injector combination is comprised of a seedlings holder, a block restraint, a cavity tool apparatus, a metering apparatus, an injection apparatus and optionally, a bore closing apparatus. The combination may be manually operated or may be automated.

BACKGROUND OF THE INVENTION

[0001] Reforestation is often carried out by outplanting seedlings thathave been grown in seedling nurseries. The seedlings may be bare rootstock or, more commonly, the root is enveloped in growth medium in theform of a plug in a container—this latter is referred to ascontainerized stock. Outplanting of containerized stock, therefore,involves placing the plug into soil at the reforestation site.

[0002] For the purposes of this specification, the term “plug” will beconsidered to include pellets—for example, Jiffy™ pellets—and any othersuitably retained growth medium, for example, growth medium in multiplecavity containers such as styroblocks. A number of plugs are typicallyretained in a block. For the purposes of this specification, the termblock will, therefore, refer to any container that has a plurality ofcavities each which holds a plug. Further, the term “fertilizer” will beconsidered to include both organic and inorganic forms of fertilizer.

[0003] To produce containerized stock, the seedlings are seeded directlyinto the plug, which has been prepared in advance, by filling a plugcavity with a growth medium. Typically, the growth medium is inert andis, for example, comprised of peat or a mixture of peat, vermiculite andsand. As the medium is very low in plant nutrients, fertilizer isprovided either as a slow-release fertilizer that is included in themix, or through fertigation.

[0004] Commonly, slow-release fertilizers are available as prills. Inthis context, “prill” is encapsulated fertilizer in the form of a bead.A prill in the context of conifer seedlings growth is chemical ororganic fertilizer encased in a polymeric coating made of plastic.Alternatively, granular formulations, both organic and inorganic, may beused that slowly release the fertilizer. These slow-release fertilizersmay be added to the plug at the time of sowing with the objective ofproviding a residual load to the seedling once it is lifted andoutplanted. However, regardless of the type of slow-release fertilizerused, much of it has been expended by the time the seedling is ready tobe lifted.

[0005] Once a seedling reaches the prescribed height, caliper anddevelopmental stage, it is lifted. At this time, it may be outplanteddirectly, as occurs with the “hot lift” seedlings, or it may be placedin cold storage, where it will remain over the winter. At the end of thecold storage period, the seedling is thawed and outplanted directly intothe reforestation site.

[0006] Establishment of the seedling in the reforestation site is acritical step in the reforestation process. Hence there has beenresearch on methods of increasing the rate of early growth. Frequently,seedling growth following outplanting is limited by a lack of adequatenutrients.

[0007] Research to increase the availability of nutrients to theseedling following outplanting has been extensive and has focussed onsuch techniques as co-cultivating mycorhizal fungi with the seedlingroots in the nursery, placing fertilizer “tea bags” in a hole next tothe hole that the plug is planted into at the reforestation site (U.S.Pat. Nos. 5,022,182 and 5,317,834), and studying root growth todetermine ways to increase the seedling's access to the limited soilnutrients. Limited fertilizer spray programs have also been implemented,but unfortunately, these often result in the brush and weeds outgrowingthe seedlings. When this occurs, the brush and weeds have to becontrolled, adding further expense to the cost of reforestation.

[0008] Despite the concern about the availability of nutrients to theseedling following outplanting, fertilization at lift, rather than at orfollowing outplanting, does not appear to have been actively pursued.Hence the prior art for such an approach appears to be limited to fieldcrop fertilizers, crop seeders and the lifting and packaging equipmentcurrently employed in seedling nurseries.

[0009] There are many patents that disclose devices and methods forinjecting materials, including fertilizer into soil. These have beendeveloped for field crops, and not for containerized crops, such asconifer seedlings. For example, U.S. Pat. No. 5,394,812 discloses adevice and method to inject polymeric materials into soil. The inventionis based on a fluid delivery system, with pumps and monitors to controlthe flow rate. The monitor is in the form of a float valve. The fluidwith the polymer therein is delivered to a series of apertures by meansof a high pressure pulse.

[0010] U.S. Pat. No. 4,907,516 discloses a device and method for pulsedinjection of liquid fertilizer into the soil. A solenoid control valveoperates intermittently to interrupt the flow of liquid in order toprovide liquid fertilizer to the nozzle in a series of short pulses.Penetration of the fertilizer into the soil is dependent upon the forceof the jet of liquid through the nozzle.

[0011] Seeders for various purposes are previously known. U.S. Pat. No.6,237,514 discloses an apparatus and method for disbursing agricultureseeds and other particulate materials into soil. A hopper supplies seedsto pockets that are located on sprocket wheels. The seeds are retainedin the pocket by a housing that abuts the sprocket wheels. The number ofseeds that are retained in each pocket is dependent upon the seed sizeand the pocket size. Rotation of the sprocket wheels to an open positionin the housing results in release of the seeds. The seeds drop withoutassistance and land on the soil. Seed bed preparation therefore iscarried out separately prior to seeding.

[0012] U.S. Pat. No. 6,273,648 discloses apparatus providing evendistribution of air-entrained particulate material to headers andultimately to delivery nozzles. Specifically, the patent discloses aconveyor tube and distribution header for use with pneumatic seeders.Turbulence is used within the conveyer tube to propel the seeds towardthe distribution head. The distribution head receives the seeds througha flow inlet and then divides the flow into a number of outlet ports.

[0013] Another apparatus for dispensing granular or particulatematerials is disclosed in U.S. Pat. No. 5,189,965. The apparatus isdesigned to uniformly discharge a predetermined quantity of granularmaterial at a predetermined rate of application. A hopper is used tofeed a metering system that has a number of rollers with pockets toreceive the granular material. As the rollers turn, the granularmaterials are released into segregated metering channels and arepneumatically propelled through a delivery system. Hence, a continuousstream of granular or particulate materials is dispensed onto the soil.

[0014] The nursery industry employs mechanized planters for emblings(somatic embryos) and seeds. Essentially, a dibbler is used to create adepression in the seed bed and seeds or emblyings are dropped into thedepression. The seed bed may be a transplant bed. Alternatively, theseeds may be sown directly into the plugs. The plugs are arranged in ablock such as a styroblock.

[0015] Typical styroblocks are each comprised of a styrofoam-typepolymer in the form of a block with plug cavities. The plug cavities aregenerally slightly conical and are wide at the top of the block,narrowing to a small hole at the bottom of the block. The number of plugcavities is variable, as are the size and volume of the plug cavities;all are dependent upon the stock type that is being grown or the desiredspecifications of the final product.

[0016] The process of lifting the seedlings from the blocks inpreparation for cold storage or planting is generally mechanized,although the operation is still done manually at some nurseries.Usually, the block is grasped in a holding device, a series of pins arealigned with the plugs in a row-by-row manner and the pins are pushedinto the plugs pneumatically, resulting in extraction of the seedlingsin their plugs. The seedlings then fall onto a moving culling bed, wherethey are manually checked for size and morphology, grouped into sets ofseedlings and wrapped as bundles in a plastic-type film, such as SaranT.

[0017] To Applicant's knowledge, fertilization at lift has notpreviously been integrated into the lifting process. This, in part,reflects the difficulties in developing machinery and methodology thatcan be integrated into the nursery operations, and that does not damagethe seedlings.

[0018] At lift, the plugs are small, soft and wet. Furthermore, they areclose together, especially in the size 410 blocks (112 plugs of 80 mL),which are the most common block size used. The plugs are easilydislodged from the blocks, as the blocks are designed for easy removalof the seedlings at lift. The styroblocks must be treated with care asthey are not very durable or rigid.

[0019] The preferred fertilizer for fertilizing conifer seedlings atlift is a slow-release prill or a granular type of fertilizer. Theprills are fragile, as the outer coating is usually a thin, plasticpolymer. The plastic coating is also hygroscopic and consequently,becomes soft and sticky in high-humidity environments. Similarly,granular fertilizer is hygroscopic and will become soft and sticky inhigh-humidity environments. Additionally, both granular fertilizer andprills tend to adhere to surfaces when force is applied. This makesmechanical insertion difficult as they will tend to clog the injectiontubes.

[0020] The seedlings are also fragile. The aerial tissue is frequentlytall, with many needles, but little branching. The root system is oftenquiescent at the time of lift, and therefore more susceptible to damage.

[0021] Any mechanized method of application has to accommodate theforegoing constraints.

SUMMARY OF THE INVENTION

[0022] An aspect of the present invention is a drill/injectorcombination that delivers various plant growth modulators (e.g.fertilizer, pesticide etc.) to a plug at lift. Lift may occur prior totransplanting, as occurs in a transplant nursery, or prior to coldstorage, or prior to outplanting. In each case, injection of plantgrowth modulators into the interior of the plug from the plug's topsurface, as contrasted with deposit of such material onto the surface ofthe plug, could result in perturbation of the seedling.

[0023] Examination of seedling morphology indicates that there are alarge number of crown roots at the top of the plug. In addition, thelocation of the stem is variable in the plug and the seedling hassubstantial aerial tissue. These factors may make it difficult to injectfertilizer into the top of the plug, as damage to the any part of theplant including the root system, stem or aerial tissue could reduceoutplanting success, measured as survival and growth in the first fewyears following outplanting. Consequently, injection is preferably intothe bottom of the plug. The present invention provides an apparatus forinjection of the plant growth modulator into the bottom of the plug,preferably by pneumatically injecting the plant growth modulator intothe plug.

[0024] As mentioned above, the hole at the bottom of the plug is small.This places a size constraint on the injection equipment.

[0025] For injection into the bottom of the plug, the blocks arepreferentially placed on their sides. This promotes retention of aspecific dose of fertilizer; if the blocks are upright and the plugs areinjected from below, the fertilizer tends to fall out of the plug—evenwhen all the operations are performed with the seedlings on their sidethere is loss of fertilizer. Further, more air pressure and a higher airflow would be required to inject from below as compared with injectingfrom the side. As a consequence, the seedlings should be supported, asthey may bend and be damaged if left unsupported.

[0026] In order to successfully inject plant growth modulator into theplug, it is preferable to pre-form a bore and a port in the plug. Thebore is preferably formed by drilling with a cavity drilling tool whichis comprised of a specially formed drill bit and a suitable drive.Drilling is preferably through the bottom of the plug. As the drill bitreaches the end of its stroke, a distal tip of the drill bit penetratesa top end of the plug and produces the port. The port allows air to beexpelled from the bore. By having a shoulder on the drill bit between awide cylindrical body and a narrow distal tip, a shoulder is createdwithin the bore. The narrowing of the bore afforded by the shoulderimpedes movement of the plant growth modulator from the bore into theport. Further, the smaller diameter of the narrow distal tip and itsflexibility reduces the risk of damage by the drill bit to the seedling.

[0027] In order to optimize the injection procedure, the charge (dose)of plant growth modulator injected into each plug should be controlled.Assuming that a metering system of the sort disclosed in U.S. Pat. No.5,189,965 is used, the correct dose can be applied by selecting theappropriate metering roller, which forms part of the metering rollerapparatus. Each metering roller has pockets sized to deliver a specificamount of plant growth modulator, and different rollers have differentpocket sizes. Once the dose has been determined, the appropriatemetering roller is used to deliver plant growth modulator to the to theindividual injectors, which deliver the charge to the plug. This ispreferably accomplished with a pneumatic injection system.

[0028] Once the plug has been injected, it is preferable to close thebore at the bottom of the plug. This can be accomplished with a borecloser or a paste injector. Closing the bore facilitates retention ofthe plant growth modulator in the bore.

[0029] Preferably, drilling occurs in at least one self-contained set ofplugs, while at the same time injection is occurring in at least oneadjacent self-contained set of plugs, while bore closing is occurring inyet another self-contained set of plugs. The sets are then laterallydisplaced so that the drilled set is positioned for injection, theinjected set are positioned for closing, the closed set removed, and afresh set is positioned in place for drilling, thereby minimizing thetime required to drill, inject and close a series of such plug sets. The“set” of plugs may conveniently be a row of plugs in a block, or in amore expensive facility, could be an entire block of plugs, providedthat the plugs may be maintained in satisfactory alignment for thedrilling and injection operations. Accordingly, it is preferable toalign and then restrain the block during drilling. An indexing bar isemployed to align the various tools with the plugs, and a clamp holdsboth a block restraint and a seedling holder in place.

[0030] The seedling holder reduces damage to the aerial tissue of theseedlings, by supporting and holding them in one place during thedrilling, injecting and closing operations. Preferably, the seedlingholder is comprised of a series of guides spaced to accept a row ofseedlings, that slide between the row and support the aerial tissue ofthe seedlings. More preferably, the seedling holder has a series ofdividers. The dividers are biased from the guides in an open position toallow the seedling to slide into place, and then close onto the guidesin the closed position to hold the seedlings.

[0031] In the preferred embodiment of the invention, the operations areautomated, and may, for example, be controlled by a timer, amicro-controller or a microprocessor.

[0032] In one embodiment of the invention, a drill bit is provided forpreparing a plug for subsequent injection of plant growth modulator intothe plug. The drill bit has a distal end, a body and a shoulder betweenthe distal end and the body. A bore is created in the plug by the drillbit by rotating the tool with a suitable drive. Exit of the distal endof the drill bit through the top of the plug results in the formation ofa port for release of air during injection of the plant growth modulatorinto the bore. The drill bit is preferably comprised of a malleablemetal such as aluminum.

[0033] In another embodiment of the invention, a cavity drillingapparatus is provided, which comprises a series of drill bits that arerotationally mounted along a head and spaced in order to align with theplugs of the container. At least one coaxially mounted bearing locatesthe drill bits in the head. The drill bits are coupled to a suitabledrive.

[0034] In one embodiment of the invention, a metering apparatus isprovided, comprising a metering roller, at least two bolts and aperforated cover. The metering roller has a series of pockets, sized toaccept a specific and predetermined amount of plant growth modulator.Rotation of the metering roller from a first position, wherein thepockets accept plant growth modulator, to a second position, wherein thepockets are aligned with perforations in the perforation plate resultsin plant growth modulator being delivered in specific and predetermineddoses. The metering roller is rotatably mounted on the perforation plateby at least one bolt at one end and at least one bolt at the opposingend. The metering roller is preferably comprised of a high densityplastic polymer. Preferably, the metering roller further comprises aflap. The flap extends the length of the metering roller and rests onthe metering roller.

[0035] In a preferred embodiment of the invention, the metering rollerpreferably subtends a hopper.

[0036] In one embodiment of the invention, an injector is provided toinject plant growth modulator into a plug. The injector is comprised ofa pneumatic injection tube, a propellant port, a charge collectionchamber and a nozzle. The collection chamber is located between thepropellant port and the nozzle and is proximal to the meteringapparatus. Plant growth modulator that collects in the collectionchamber is forced into the plug in a discrete charge. Preferably, theplant growth modulator is air-entrained.

[0037] In another embodiment of the invention, an injection apparatus isprovided, which comprises a series of injectors that are positioned on ahead. The injectors are spaced in order to align with the plugs of thecontainer during injection of the bores.

[0038] In another embodiment of the invention, a bore closing tool isprovided.

[0039] In another embodiment of the invention, a bore closing apparatusis provided, which comprises a series of bore closers that arepositioned on a head and are spaced in order to align with the plugs ofthe container during closing of the bores. Preferably, the bore closerhas a paddle located on a distal end.

[0040] In an alternate embodiment of the invention, a paste extruder isprovided.

[0041] In yet another aspect of the invention, a series of pasteextruders are positioned on a head and are spaced in order to align withthe plugs of the container during closing of the bores.

[0042] In another embodiment of the invention, there is a hydraulicinjector, wherein the propellant port is replaced with a hydraulic tubewhich has, at a distal end, a hydraulic ram. Actuation of the hydraulicram forces air through the pneumatic injection tube, entraining theplant growth modulator in the collection chamber, and releasing itthrough the nozzle.

[0043] In another embodiment of the invention, the hydraulic injector iscontrolled by, for example, a microprocessor, such that pulses of airare delivered to the pneumatic injection tube. Each pulse of air resultsin delivery of one charge of plant growth modulator. After each pulse,the collection chamber is reloaded with plant growth modulator.

[0044] In another embodiment of the invention, there is a hydraulicinjection apparatus, which comprises a series of injectors that arepositioned on a head and are spaced in order to align with the plugs ofthe container during injection of the bores.

[0045] In yet another embodiment of the invention, there is a fluidinjector, comprising a fluid delivery tube, a collection chamber, afluid injection tube and a nozzle. A pump injects fluid into the fluidinjection tube from the fluid delivery tube, thereby fluid-entrainingthe plant growth modulator in the collection chamber, and releasing itthrough the nozzle.

[0046] In yet another embodiment of the invention, there is a fluidinjection apparatus, which comprises a series of injectors that arepositioned on a head and are spaced in order to align with the plugs ofthe container during injection of the bores.

[0047] In another embodiment of the invention, the fluid injector iscontrolled by, for example, a microprocessor, such that pulses of fluidare delivered to the fluid injection tube. Each pulse of fluid resultsin delivery of one charge of plant growth modulator. After each pulse,the collection chamber is reloaded with plant growth modulator.

[0048] In another embodiment of the invention there is a seedling holdercomprising a framework and a series of guides and dividers. The guidesare aligned to separate the seedlings into rows. Each row of seedlingsis then retained by the dividers, which are articulated and can closeover the seedlings.

[0049] In another aspect of the invention, a clamp clamps the seedlingholder to the block restraint.

[0050] In one embodiment of the invention, there is an injection slideupon which are housed a cavity drilling apparatus, an injectionapparatus and a bore closing apparatus.

[0051] In a preferred embodiment of the invention, the injection slideis further provided with a positioning dowel.

[0052] In one embodiment of the invention, there is a cavity tool and aninjector. The cavity tool is comprised of a drill bit that is coupled toa suitable selected drive.

[0053] In another aspect of the invention, there is a cavity tool, aninjector and a bore closing tool.

[0054] In another aspect of the invention, there is a cavity tool, aninjector and a metering apparatus.

[0055] In another aspect of the invention, there is a cavity tool, aninjector, a metering apparatus and a bore closing tool.

[0056] In another aspect of the invention, there is a cavity drillingapparatus and an injection apparatus.

[0057] In another aspect of the invention, there is a cavity drillingapparatus, an injection apparatus and a bore closing apparatus.

[0058] In another aspect of the invention there is a cavity drillingapparatus, an injection apparatus and a metering apparatus.

[0059] In another aspect of the invention there is a cavity drillingapparatus, an injection apparatus, a metering apparatus and a boreclosing apparatus.

[0060] In another aspect of the invention there is a block restraint andan injection apparatus.

[0061] In another aspect of the invention there is a block restraint, acavity drilling apparatus and an injection apparatus.

[0062] In another aspect of the invention, there is a block restraint, acavity drilling apparatus, an injection apparatus and a meteringapparatus.

[0063] In another aspect of the invention there is a block restraint, acavity drilling apparatus, an injection apparatus and a bore closingapparatus.

[0064] In another aspect of the invention there is a block restraint, acavity drilling apparatus, a metering apparatus, an injection apparatusand a bore closing apparatus.

[0065] In another aspect of the invention there is a seedling holder andan injection apparatus.

[0066] In another aspect of the invention there is a seedling holder, acavity drilling apparatus and an injection apparatus.

[0067] In another aspect of the invention there is a seedling holder, acavity drilling apparatus, a metering apparatus and an injectionapparatus.

[0068] In another aspect of the invention there is a seedling holder, acavity drilling apparatus, an injection apparatus and a bore closingapparatus.

[0069] In another aspect of the invention there is a seedlings holder, acavity drilling apparatus, an injection apparatus, a metering apparatusand a bore closing apparatus.

[0070] In another aspect of the invention, there is a block restraint, aseedling holder and an injection apparatus.

[0071] In another aspect of the invention there is a block restraint, aseedling holder, a cavity drilling apparatus and an injection apparatus.

[0072] In another aspect of the invention there is a block restraint, aseedling holder, a cavity drilling apparatus, a metering roller and aninjection apparatus.

[0073] In another aspect of the invention there is a block restraint, aseedling holder, a cavity drilling apparatus, an injection apparatus anda bore closing apparatus.

[0074] In another aspect of the invention there is a block restraint, aseedling holder, a cavity drilling apparatus, a metering apparatus, aninjection apparatus and a bore closing apparatus.

SUMMARY OF THE DRAWINGS

[0075]FIGS. 1A and B. An isometric view of a drill/injector combination,according to the invention. FIG. 1A shows a left hand view and FIG. 1Bshows a detail right hand view of the receiving tray, block restraintand seedling holder.

[0076]FIG. 2. A plan view of the cavity drilling apparatus, theinjection apparatus and the bore closing apparatus of FIGS. 1A and 1B.

[0077]FIG. 3. An isometric view of the seedling holder shown as part ofthe drill/injector combination of FIGS. 1A and 1B.

[0078]FIG. 4. An isometric view of a part of the seedling holder shownin FIG. 3.

[0079]FIGS. 5A, B and C. A longitudinal mid-section view through a plugand plug cavity in a block. 5A shows the plug prior to preparation ofthe bore. FIG. 5B shows the plug during preparation of the bore. Correctplacement of a drill bit is shown according to an aspect of theinvention. FIG. 5C shows the plug after preparation of the bore.

[0080]FIG. 6. An isometric view of a cavity drilling apparatus shown aspart of the invention in FIGS. 1A and 1B.

[0081]FIG. 7. An exploded view of the cavity drilling apparatus shown inFIG. 6.

[0082]FIG. 8. A side view of the drill bit according to the invention.

[0083]FIG. 9. An isometric view of an injection slide as shown as partof the invention in FIGS. 1A and 1B.

[0084]FIG. 10. An isometric view of a metering apparatus, with theinjection tube of the injection apparatus exploded therefrom, as shownas part of the invention in FIGS. 1A and 1B.

[0085]FIG. 11. An explored view of the metering apparatus shown in FIG.10.

[0086]FIG. 12. An isometric view of an injection apparatus as shown aspart of the invention in FIGS. 1A and 1B.

[0087]FIG. 13. An isometric view of a bore closing apparatus shown aspart of the invention in FIGS. 1A and 1B.

[0088]FIG. 14. An exploded view of a bore closing apparatus shown inFIG. 13.

[0089]FIG. 15. An exploded cross section of a second embodiment of theinvention, showing a paste extruder.

[0090]FIG. 16. An isometric view of a second embodiment of the inventionshowing a paste extruder head.

[0091]FIG. 17. An exploded view of the paste extruder head shown in FIG.16.

[0092]FIG. 18. A plan view according to the invention showing anindexing bar and a dog, mounted to the receiving tray.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0093] A drill/injector combination, generally indicated as 30 and shownin FIG. 1A can be integrated into standard lift operations in thenursery and is used for fertilizing plugs with prills or granularmaterial at lift. The drill/injector combination 30 is comprised of ablock restraint 32, a seedling holder 34, a cavity drilling apparatus36, a metering apparatus 38, an injection apparatus 40, and a boreclosing apparatus 42. The various systems are sub-combinations of theentire injection apparatus. Prills are the preferred form of slowrelease fertilizer, but they are difficult to inject because of thefragile outer coating and their hygroscopic nature. Hence, thedrill/injector combination 30 is designed to accommodate these featuresof the prills.

[0094] Blocks 44 or other seedling containers are preferably placed ontheir side and are moved to the seedling holder 34 by a loading conveyor46. Once at the seedling holder 34, the block 44 is clamped to theseedling holder 34 by a clamp 48.

[0095] The block restraint 32 is comprised of a receiving tray 50 with achannel 52 that is wide enough to accommodate the block 44 on its side.Both the receiving tray 50 and the channel 52 extend longitudinallybetween the loading conveyor 46 and a lifting conveyor 58. A stop 54 toreceive the block 44 is preferably an L-shaped member and is mounted onthe block restraint 32.

[0096] The seedling holder 34 is comprised of a series of guides 62 anddividers 64 mounted on two open boxes; a bottom box 68, and an end box70. The bottom box 68 is mounted perpendicular to the end box 70 andholds the clamp 48 to clamp the seedling holder 34 and block restraint32 in place on the receiving tray 50. As the block 44 moves into theseedling holder 34, the guides 62 separate the seedlings 56 into rows.Once all the seedlings 56 in the block 44 are in the seedling holder 34,and the block 44 is in the block restraint 32, both are locked inposition with the clamp 48. The dividers 64 are then closed to hold theseedlings 56. This geometry facilitates maintenance of the desiredalignment of the block 44 and the seedlings 56 with each other and,therefore, tends to avoid twisting and bending of the seedlings 56 bythe seedling holder 34.

[0097] Two opposing side members 72, 74 of the end box 70 support theseries of guides 62 and dividers 64. The guides 62 are preferably madeof metal and are trapezoid-shaped plates that are preferably mountedhorizontally to the side members 72, 74. The acute angle of thetrapezoid is located on a loading end 78 of the seedling holder 34 suchthat it is proximal to the block 44. An acute angle is preferred over aright angle, as it assists in coaxing each seedling 56 onto the guidestarting with the stem, which is sturdy and has few needles and endingwith the fragile aerial growth.

[0098] A series of dividers 64, preferably two per guide 62 are mountedon hinges 76 that are mounted on the side members 72, 74 and extendbetween the side members 72, 74. The dividers extend between the sidemembers 72, 74. The dividers 64 provide a space 82 such that a row ofseedlings 56 can be moved horizontally through the space 82 when thedividers 64 are in the open position. When the dividers 64 are closed,the seedlings 56 are gently restrained. The dividers 64 are preferablymade of a pliable material such as webbing or rubber, in order to reducethe potential for damage to the seedlings 56.

[0099] Once the seedlings 56 are supported in the seedling holder 34, adrill bit 84 is employed to drill a bore 86 and a port 88 into the plug90. As shown in FIG. 5B, the drill bit 84 enters the plug 90 through asmall hole 92 that is in the bottom of each plug cavity 94, then entersthe plug 90 at a bottom end 96 and progresses through the plug 90,creating the port 88 for air release at a top end 98 of the plug 90.

[0100] Proper alignment and operation of the cavity tools 84 is providedby the cavity drilling apparatus 36. Preferably, the cavity drillingapparatus 36 is comprised of a head (generally indicated by number 100)that retains a series of cavity tools 84 that are coupled to a driveshaft 106 (FIGS. 6 and 7). As shown in FIG. 6, the cavity tools 84 arealigned along the head 100 such that they will be in alignment with theplugs 90 in at least one row. Preferably, the head 100 is sufficientlylarge enough to hold a gang of cavity tools 84 corresponding in numberand location to the plugs 90 in a 410 block 44, the designation “410”being a size designation used in the industry. It is proposed thatdifferent heads 100 will be available for different block sizes.

[0101] The head 100 is comprised of two opposing sides 108, 110, a base112, a top 114, a mount 116, a dust cap 154 and a drill bit holder 118.The sides 108, 110, base 112, top 114, mount 116 and dust cap 154 areattached to one another to form a box 120. The drill bit holder 118 ishoused in the box 120 and is attached to the sides 108, 110 of the box120. Apertures 122 in the drill bit holder 118 are located so as to bein register with the plugs 90 of the block 44. Similarly, the top 114 ofthe head 100 has a series of openings 124 that are in register with theplugs 90 of the block 44. The cavity tools 84 are positioned such thatone tool 84 is aligned with one opening 124 and a corresponding aperture122. This aligns one drill bit 84 with one plug 90. The dust cap 154impedes entry of dust into the head 100.

[0102] The cavity tools 84 are approximately torpedo-shaped, but formedwith an annular shoulder 134, for the purpose previously stated (seeFIG. 8). Further, a distal tip 130 of the drill bit 84 is conical. Theshape of the drill bit 84 has been shown to reduce damage to theseedling roots during drilling as the roots are pushed aside as thedrill bit 84 advances. A long wide, cylindrical body 126 extends betweena proximal end 128 and a distal tip 130, which is narrow and terminatesin a point 132. A shoulder 134 between the cylindrical body 126 and thedistal tip 130 is preferably at 20 degrees relative to a longitudinalaxis 136. The distal tip 130 is long enough to extend out through thetop end 98 of the plug 90. The drill bit 84 is preferably aluminum or ametal with similar malleability, or a flexible plastic polymer as hardermaterials may damage the roots or aerial tissue.

[0103] Rotatably mounted proximally on the drill bit 84 and locatedbetween the top 114 of the head 100 and the drill bit holder 118 is aninner bearing 138, a spacer 140 and an outer bearing 142 (see FIG. 6).The bearings 138, 142 rotatably mount the drill bit 84 in the drill bitholder 118. The proximal end 128 of the drill bit 84 is preferably matedto a first mitre gear 144 in order to drive the cavity tool. The firstmitre gear 144 engages a second mitre gear 146 with a peripheral rotaryengagement of approximately 90 degrees. The second mitre gear 146 ismounted coaxially on the drive shaft 106 and is driven by the shaft 106.A guide 150 on either side of the second mitre gear 146 separates itfrom at least one spanner 152. The drive shaft 106 is rotatably mountedon the spanners 152, which bridge the drill bit 84 holder and the top114 of the head 100.

[0104] The cavity tools 84 are able to rotate freely about alongitudinal axis 136 and are driven by means of the drive shaft 106,which is coupled to and driven by the output shaft of a gear box (notshown). The gear box, in turn, is coupled to and driven by a motor (notshown). The rate of rotation and penetration of the cavity tools 84 iscontrolled to facilitate displacement of the seedling roots so that theroots are pushed aside rather than being damaged. The preferred rate ofrotation in a prototype apparatus was found to range from about 80 toabout 400 rpm. Penetration by the cavity tools 84 is controlled suchthat the tools 84 move distally longitudinally far enough to exitthrough the top end 98 of the plugs 90 in order to create the ports 88.The cavity tools 84 are then retracted and moved into alignment with thenext row or rows of plugs 90.

[0105] Placement of the cavity tools 84 is controlled by an injectionslide 158. The head 100 of the cavity drilling apparatus 36 is affixedto a plate 156 by the mount 116 and the plate 156 is vertically mountedon the injection slide 158. The injection slide 158 is comprised of afoot 160, four risers 162 and a frame (generally indicated by number164)(see FIG. 9). A support rod 166 extends between a front member 168and a back member 170 of the frame 164. The plate 156 is coupled to ahanger 172, which hangs from the support rod 166. Movement of the head100 towards and away from the block 44 is accomplished by sliding thehanger 172 along the support rod 166. This is preferably controlled by apress which is preferably hydraulically actuated. Correct placement ofthe cavity drilling apparatus 36 is promoted by a positioning dowel 173which extends outwardly from the plate 156 and is received by anaperture 175 in the block restraint 32.

[0106] Correct operation of the cavity drilling apparatus 36 results ina plug 90 with a wide bore 86, which will receive the fertilizer, and anarrow port 88 for air release from the plug 90 (see FIG. 5C). Such aplug 90 is ready for injection using injectors 178 on the injectionapparatus. The block 44 remains clamped by the block restraint 32, andthe seedling holder 34 continues to support the seedlings 56 during theinjection operation. The injection apparatus 40 is mounted beside thecavity drilling apparatus 36 such that the series of cavity tools 84 arealigned with one row of plugs 90 and the injection apparatus 40 isaligned with the adjacent row of plugs 90 (FIG. 1A).

[0107] Fertilizer is delivered from a hopper 174 through an orifice 180to the metering apparatus 38 prior to entry into the injection apparatus40 (see FIG. 10). The hopper is affixed to the injection slide 158 by asupport 176. The metering apparatus 38 is comprised of a metering roller182, at least two bolts 184 and a perforated cover 188 (see FIG. 11).The perforated cover 188 is affixed to the hopper 174 and the meteringroller 182 is rotationally mounted thereon by the bolts 184. Preferably,the perforated cover 188 is provided with a flap 189 that extends alongits length.

[0108] The metering roller 182 has pockets 190 sized to hold the volumeof fertilizer needed in a particular dose. A number of metering rollers182 are, therefore, available in order to provide a range of doses. Forexample, a series of 6 rollers deliver 0.5 g, 1.0 g, 1.5 g, 2.0 g, 2.5 gand 3.0 g of a given standard of fertilizer. The metering roller ispreferably comprised of a high density plastic polymer. The meteringroller 182 rotates, by means of a handle 186 and delivers the doses to aseries of inlets 192 of a series of pneumatic injection tubes 194through perforations 196 of the perforated cover 188 and then continuesits rotation to position the pockets 190 below the hopper 174 in orderto refill. In this position, air flow from the pneumatic injection tubes194 into the hopper 174 is impeded. The reduced air flow assists inremoving any residual fertilizer from the pockets 190 and assists inremoving residual fertilizer from the pneumatic injection tubes 194prior to refilling.

[0109] Each injector 178 is comprised of a pneumatic injection tube 194,a charge collection chamber 198, a nozzle 200 and a propellant port 202.In one embodiment, the collection chamber 198 is simply a bend in thetube, that projects below both the inlet 192 and the nozzle 200 (seeFIG. 12). The propellant port 202 is located between the inlet 192 andthe collection chamber 198. It is in pneumatic communication with thepneumatic injection tube 194. Pulses of air enter into the pneumaticinjection tube 194 under the control of a pneumatic pump (not shown).The velocity and volume of air in a given pulse is controlled by acontroller (not shown), for example, a microprocessor, such that a timedsequence of controlled pulses of air are delivered to the pneumaticinjection tube 194. The air pressure is preferably 15±2 psi and theduration of the pulse is preferably 0.6±0.5 second. Each pulse of airpropels the fertilizer, which has been delivered to the collectionchamber 198 by the metering apparatus 38, into the nozzle 200, which issized to mate with the bore 86. The air-entrained fertilizer then enterseach bore 86 in a selected set of plugs 90 where it is retained. Excessair escapes through the port 88 in the plug 90. The bore 86 has ashoulder 204 formed by the shoulder 134 of the drill bit 84 (see FIGS.3B and 6). This assists in retaining the fertilizer in the bore 86.After each pulse, the collection chamber 198 of each injector 178 isreloaded with fertilizer.

[0110] The injection apparatus 40 is mounted on the same plate 156 thatthe head 100 of the cavity drilling apparatus 36 is mounted on. Hence,movement into and out of the block 44 is again controlled by sliding thehanger 172 along the support rod 166 of the injection slide 158.

[0111] The final step involves closing the bore 86. A bore closer 206engages the bottom end 96 of the plug 90 and exerts pressure on thebottom end 96 of the plug 90. In one embodiment (see FIG. 13), a paddle208 is mounted on a distal end 210 of the bore closer 206 and the borecloser is rotated, while pressure is exerted on the bottom end 96 of theplug 90. In another embodiment the bore closer has a concave end (notshown) that accepts the bottom end 96 of the plug 90.

[0112] Proper alignment and operation of the bore closers 206 isprovided by the bore closing apparatus 42. Preferably, the bore closingsystem 42 is comprised of a head 212 that retains a series of boreclosers 206 that are coupled to a drive shaft 216 (see FIG. 14). Thebore closers 206 are aligned along the head 212 such that they will bein alignment with the plugs 90 in at least one row. Preferably, the head212 is sufficiently large enough to hold a gang of bore closers 206corresponding in number and location with the plugs 90 in a 410 block44. It is proposed that different heads 212 will be available fordifferent block sizes.

[0113] The head 212 is comprised of two opposing sides 218, 220, a base222, a top 224, a mount 226, a dust cap 236 and a bore closer holder228. The sides 218, 220, base 222, top 224 and dust cap 236 are attachedto one another to form a box 230. The bore closer holder 228 is housedin the box 230 and is attached to the sides 218, 220 of the box 230.Apertures 232 in the bore closer holder 228 are located so as to be inregister with the plugs 90 of the block 44. Similarly, the top 224 has aseries of openings 234 that are in register with the plugs 90 of theblock 44. The bore closers 206 are positioned such that one closer 206is aligned with one opening 234 and a corresponding aperture 232. Thisaligns one drill bit 84 with one plug 90.

[0114] The mount 226 attaches the bore closing apparatus 42 to the sameplate 156 to which the head 100 of the cavity drilling apparatus 36 isattached. Hence movement into and out of the block 44 is againcontrolled by sliding the hanger 172 along the support rod 166 of theinjection slide 158. The dust cap 236 impedes entry of dust into thehead 212.

[0115] Rotatably mounted proximally on the bore closer 206 is an innerbearing 238, a spacer 240 and an outer bearing 242. The bearings 238,242 rotatably mount the bore closer 206 in the bore closer holder 228. Aproximal end 244 of the bore closer 206 is mated to a first mitre gear246 in order to drive the bore closer 206. A second mitre gear 248engages the first mitre gear 246 with a peripheral rotary engagement ofapproximately 90 degrees. The second mitre gear 248 is mounted coaxiallyon the drive shaft 216 and is driven by the shaft A guide 252 on eitherside of the second mitre gear spaces it from spanners 254. The driveshaft 216 is rotatably mounted on the spanners 254, which bridge thebore closer 206 and the top 224 of the head 212. The bore closer 206preferably rotates at 10-400 rpm.

[0116] In a second embodiment there is provided a paste extruder 256 asa means for closing the bore 86 (see FIG. 15). A suitable paste isbiodegradable and is sufficiently viscose to remain in the bore 86 afterinjection. The paste extruder 256 is preferably air-actuated and has aplunger 258 housed within a chamber 260. The plunger is depressed whenair is forced through a pneumatic tube 261. The chamber 260 has anaperture 262 distal to the plunger 258. Actuation of the plunger 258forces a predetermined amount of paste from the chamber 260, through theaperture 262 and into the bore 86 of the plug 90. The aperture 262 issized to fit in the small hole 92 in the bottom of the plug cavity 94and is preferably also sized to enter into the bore 86. The depth of theextrusion is controlled by the force exerted on the plunger 258, theviscosity of the paste and depth of the paste extruder 256 in the bore86.

[0117] A series of paste extruders 256 are mounted on a head 264 that issimilar to that described above. The paste extruders 256 are alignedalong the head 264 such that they will be in alignment with the plugs 90in at least one row. Preferably, the head 264 is sufficiently largeenough to hold a gang of paste extruders 256 corresponding in number andlocation with the plugs 90 in a 410 block 44. It is proposed thatdifferent heads 264 will be available for different block sizes orconfigurations.

[0118] The head for the paste extruders 256 is comprised of two opposingsides 266, 268, a base 270, a top 272, a mount 274, a dust cap 300 and apaste extruder holder 276. The sides 266, 268, base 270, top 272 anddust cap 300 are attached to one another to form a box 278. The pasteextruder holder 276 is housed in the box 278 and is attached to thesides of the box 278. Apertures 280 in the paste extruder holder 276 arelocated so as to be in register with the plugs 90 of the block 44.Similarly, the top 272 has a series of openings 282 that are in registerwith the plugs 90 of the block 44. Each paste extruder 256 is positionedin the opening 282 and the corresponding aperture 280 in order to bealigned with the plug 90.

[0119] During the injection process, it is be necessary to repositionthe block restraint 32 and the seedling holder 34 to align thedrill/injector combination 30 with rows of plugs 90 that have not beeninjected. Contact points between the receiving tray 50 and both theblock restraint 32 and seedling holder 34 are preferably coated with amaterial such as a high density plastic polymer to reduce friction. Theblock 44 may be repositioned as needed by manually releasing and movingthe block restraint 32 and seedling holder 34 along an indexing bar 294.Different indexing bars 294 corresponding to different block sizes canbe used as needed. The indexing bar 294 has a series of stops 296 thatare spaced for alignment with the plugs 90 in a block 44 (FIG. 18). Theindexing bar 294 is affixed to the seedling holder 34 and is positionedto accept a dog 298 mounted on the receiving tray 54. Engagement of astop 296 with the dog 298 facilitates alignment of the various tools andinjectors with the plugs 90.

[0120] Once aligned, the cavity drilling apparatus 36, the injectionapparatus 40 and the bore closing apparatus 42 can be moved into andaway from the block 44 along the injection slide 158. The movement iscontrolled by a press (not shown) which is preferably hydraulicallyactuated.

[0121] Preferable, the cavity drilling apparatus 36, the injectionapparatus 40 and the bore closing apparatus 42 are mounted on theinjection slide 158 to enable drilling in at least one self-containedset of plugs 90, while at the same time, injection is occurring in atleast one adjacent self-contained set of plugs 90, and closing isoccurring in at least one self-contained set of plugs 90 adjacent toself-contained set of plugs 90 being injected. The set of plugs 90 maybe a row of plugs 90 or may be an entire block 44 of plugs 90, providedthat the plugs 90 may be maintained in satisfactory alignment for thedrilling, injecting and closing operations. Preferably, the operationsof drilling, metering, injecting and closing occur recurrently, withrestraining the block 44 and holding the seedlings 56 being in synchronywith these operations and occurring recurrently.

[0122] Once the block 44 of plugs 90 has been fertilized and the bore 86closed, the seedling holder 34 is disengaged, the block restraint 32 isdisengaged and the block 44 is moved onto the lifting conveyor 58.

[0123] The foregoing description of injecting fertilizer into plugs atlift describes the preferred methods and is not meant to be limiting. Aswould be apparent to one skilled in the art, there can be, for example,variation in the degree of mechanization, the mode of restraining andsupporting the blocks and seedlings and the type of container that isrestrained. Fertilizer may be delivered into the bore in the plug in avariety of ways, including in a fluid. Further, while the foregoingdescription is premised by way of example upon injection of fertilizer,a variety of different materials can be injected. For example,encapsulated biological material selected from the group consisting ofbacteria, fungi, nematodes, virus, and combinations thereof, pesticides,including herbicides, insecticides, and herbivore deterrents,hygroscopic materials, seed and growth adjuvants could be injected.Finally, a variety of materials may be injected into a plug that doesnot contain a seedling. For example, the method can be used to seedplugs. Similarly, it can deliver material into a plug in which a plant,rather than a seedling is growing.

What is claimed is:
 1. A drill/injector combination for use with asuitable selected charge propulsion means, for injecting a predetermineddiscrete charge of plant growth modulator into a plug, comprising: acavity drilling tool for rotary coupling to a suitable selected drive,having a rotatable drill bit for drilling a bore in the plug, and havingmeans operable to advance the tool when rotating into the plug by apredetermined distance thereby to create the bore and operable toretract the tool from the plug following the creation of the bore; aninjector for coupling to the charge propulsion means and operable toinject the charge into the bore; and metering apparatus coupled to theinjector for dispensing to the injector a metered amount of plant growthmodulator constituting at least a portion of said charge.
 2. Thedrill/injector combination of claim 1 further comprising an alignmentmeans for successively aligning the plug with the cavity drilling tooland with the injector.
 3. The combination of claim 2, including meanscontrolling the operation of the cavity drilling tool and the injectorand the alignment means, for cycling the drilling and injectionoperations so that a series of plugs may be drilled and injected insequence.
 4. A drill/injector combination for cyclable use with asuitable selected charge propulsion means, for cyclable operation toinject a predetermined discrete charge of plant growth modulator intoeach plug in a succession of plugs arranged in sets of plugs, each saidset being arranged as a predetermined array of plugs, comprising: cavitydrilling apparatus comprising an array of cavity drilling tools matingwith the array of plugs for one-to-one alignment of the drilling toolswith the plugs; each said drilling tool having a rotatable drill bit fordrilling a bore in the plug and being mounted in the cavity drillingapparatus for rotary coupling to a suitable selected drive forsimultaneously rotating the rotatable drill bits; means recurrentlyoperable to advance the rotating drill bits together into successivesets of said plugs by a predetermined distance thereby to create thebores and recurrently operable to retract the drill bits together fromsaid last-mentioned plugs following the creation of the bores; injectionapparatus comprising an array of injectors for coupling to the chargepropulsion means and recurrently operable to inject the charges into thebores of successive sets of said plugs; said array of injectors matingwith the array of plugs for one-to-one alignment of the injectors withthe plugs; metering apparatus for recurrently dispensing to each of theinjectors a metered amount of plant growth modulator; and alignmentmeans for recurrently aligning successive sets of the plugs with thedrill bits and with the injectors.
 5. The combination of claim 4,wherein the array of plugs is a linear array of equally spaced plugs,the injectors and drilling tools are mounted in mating linear arrays,and the alignment means is operable to move the array of plugsconsecutively into alignment first with the drilling tools and then withthe injectors.
 6. The combination of claim 5, wherein the injectors anddrilling tools are mounted in parallel linear arrays.
 7. The combinationof claim 5, wherein each said injector comprises a proximal chargecollection chamber coupled to the metering apparatus for receiving thecharge from the metering apparatus; a propellant port in proximalcommunication with the collection chamber for applying propellant to thecharge in the collection chamber in response to operation of the chargepropulsion means thereby to propel the charge out of the collectionchamber; and a nozzle in distal communication with the collectionchamber and whose distal tip is in operation aligned with a mating oneof said bores, for delivery of the propelled charge into thelast-mentioned bore.
 8. A drill/injector combination for cyclable use toinject a predetermined discrete charge of plant growth modulator intoeach plug in a succession of plugs arranged in sets of plugs, each saidset being arranged as a predetermined array of plugs, comprising: cavitydrilling apparatus comprising an array of cavity drilling tools matingwith the array of plugs for one-to-one alignment of the drilling toolswith the plugs; each said drilling tool having a rotatable drill bit fordrilling a bore in the plug and being mounted in the cavity drillingapparatus for rotary coupling to a suitable selected drive forsimultaneously rotating the rotatable drill bits; means recurrentlyoperable to advance the rotating drill bits together into successivesets of said plugs by a predetermined distance thereby to create thebores and recurrently operable to retract the drill bits together fromsaid last-mentioned plugs following the creation of the bores; injectionapparatus comprising an array of injectors coupled to a chargepropulsion means for recurrent injection of the charges into the bore;said propulsion means having an ON position and an OFF position suchthat in the ON position the propellant is delivered from a source ofpropellant to the injector thereby to propel the charge into the alignedbore, and in the OFF position, the propellant is impeded from deliveryfrom the source to the injector; said array of injectors mating with thearray of plugs for one-to-one alignment of the injectors with the plugs;metering apparatus for recurrently dispensing to each of the injectors ametered amount of plant growth modulator; and alignment means forrecurrently aligning the plugs with the drill bits and with theinjectors.
 9. The drill/injector combination of claim 2, wherein thedrill bit has a wide body, a narrow distal tip and a shoulder betweenthe body and the tip.
 10. The drill/injector combination of claim 8,wherein the drill bit has a wide body, a narrow distal tip and ashoulder between the body and the tip.
 11. The drill/injectorcombination of claim 9 wherein the drill bit is symmetrical about itsaxis of rotation.
 12. The drill/injector combination of claim 10 whereinthe drill bit is symmetrical about its axis of rotation.
 13. Thedrill/injector combination of claim 11 wherein the drill bit is made ofmaterial selected to promote flexing and bending of the drill bit duringuse.
 14. The drill/injector combination of claim 12 wherein the drillbit comprises a material selected to promote flexing and bending of thedrill bit during use.
 15. The drill/injector combination of claim 4,further comprising a restraint means for receiving and releasablyrestraining a block of plugs and a means for releasably coupling saidrestraint means to the alignment means.
 16. The drill/injectorcombination of claim 8, further comprising a restraint means recurrentlyoperable to receive and releasably restrain a block of plugs and a meansfor releasably coupling said restraint means to the alignment means. 17.The drill/injector combination of claim 15 further comprising a seedlingholder for supporting a set of plants contained in an array of plugs,said seedling holder having a series of guides spaced to receive andsupport the set of plants and means to releasably couple the seedlingholder to the restraint means.
 18. The drill/injector combination ofclaim 16 further comprising a seedling holder for supporting a set ofplants contained in an array of plugs, said seedling holder having aseries of guides spaced to receive and support the set of plants andmeans to recurrently couple the seedling holder to the restraint means.19. The drill/injector combination of claim 17, wherein the seedlingholder further comprises a series of dividers, said dividers beingconnectible to a suitable actuator and spaced to receive a set of plantsin an OPEN position and to hold the set of plants in the CLOSEDposition, said actuator having means to recurrently urge the dividersbetween the OPEN and CLOSED positions.
 20. The drill/injectorcombination of claim 18, wherein the seedling holder further comprises aseries of dividers, said dividers being connectible to a suitableactuator and spaced to receive a set of plants in an OPEN position andto hold the set of plants in the CLOSED position, said actuator torecurrently urge the dividers between the OPEN and CLOSED positions. 21.The drill/injector combination of claim 19 wherein the dividers arecomprised of a pliable material for holding the plants.
 22. Thedrill/injector combination of claim 20 wherein the dividers arecomprised of a pliable material for holding the plants.
 23. Thedrill/injector combination of claim 2 further comprising a bore closingtool for rotary coupling to a suitable selected drive, comprising; arotatable bore closer for closing a bore in the plug; means recurrentlyoperable to advance the rotating bore closer by a predetermined distancethereby to close the bore and recurrently operable to retract the borecloser from last mentioned plug following closing of the bore; and meansto couple the bore closing tool to the alignment means.
 24. Thedrill/injector combination of claim 4 further comprising a bore closingtool for rotary coupling to a suitable selected drive, having arotatable bore closer for closing a bore in the plug, and meansrecurrently operable to advance the rotating bore closer by apredetermined distance thereby to close the bore and recurrentlyoperable to retract the bore closer from last mentioned plug followingclosing of the bore.
 25. The drill/injector combination of claim 8further comprising a bore closing apparatus comprising an array of boreclosing tools mating with the array of plugs for one-to-one alignment ofthe bore closing tools with the plugs; each said bore closing toolhaving a rotatable bore closer for closing a bore in the plug and beingmounted in the bore closing apparatus for rotary coupling to a suitableselected drive for simultaneously rotating the rotatable bore closers;and means recurrently operable to advance the rotating bore closerstogether in successive sets of said plugs by a predetermined distancethereby to close the bores and recurrently operable to retract the boreclosers together from last mentioned plugs following closing of thebores.
 26. The drill/injector combination as claimed in claim 4 whereinthe propellant is air.
 27. The drill/injector combination of claim 26wherein the collection chamber is dimensioned and configured, and thepropellant pressure and delivery pulse are selected so that the pulseair-entrains the charge.
 28. The drill/injector combination as claimedin claim 27 additionally comprising means for recurrently pneumaticallyactuating the injection apparatus.
 29. The drill/injector combination asclaimed in claim 27 comprising means for recurrently hydraulicallyactuating the injection apparatus.
 30. The drill/injector combination asclaimed in claim 2 wherein the propellant is fluid.
 31. A seedlingholder for supporting a set plants contained in an array of plugs, saidseedling holder having a series of guides spaced to receive and supportthe set of plants and means to releasably couple the seedling holder toa restraint means.
 32. The seedling holder of claim 31, furthercomprising a series of dividers coupled to the guides, said dividersbeing connectible to a suitable actuator and spaced to receive and holda set of plants in an OPEN position and to hold the set of plants in theCLOSED position, said actuator urging the dividers between the OPEN andCLOSED position.
 33. The seedling holder of claim 32 wherein thedividers are comprised of a pliable material for holding the plants. 34.The seedling holder of claim 33 wherein the dividers are comprised ofwebbing.
 35. The seedling holder of claim 33 wherein the dividers arecomprised of a polymer.
 36. The seedling holder of claim 33 furthercomprising hinges, said hinges being coupled to the guides, wherein thedividers are mounted on hinges and the hinges have a means for applyinga biasing force to the dividers.
 37. A seedling holder for supporting aset plants contained in an array of plugs, said seedling holder having aseries of guides, a series of dividers, hinges coupled to the guides,means to recurrently couple the seedling holder to a restraint means,said dividers being mounted on the hinges and being connectible to asuitable actuator and spaced to receive a set of plants in an OPENposition and to hold the set of plants in the CLOSED position, saidactuator having means to recurrently urge the dividers between the OPENand CLOSED position, and said hinges having a means for applying abiasing force to the dividers.
 38. An injection apparatus for cyclableoperation to inject a predetermined discrete charge of plant growthmodulator into a bore in each plug in a succession of plugs arranged insets of plugs, each said set being arranged as a predetermined array ofplugs, comprising an array of injectors for coupling to a chargepropulsion means and recurrently operable to inject the charges into thebores; said array of injectors mating with the array of plugs forone-to-one alignment of the injectors with the plugs.
 39. The injectionapparatus of claim 38, wherein the array of plugs is a linear array ofequally spaced plugs, the injectors are mounted in mating linear arrays,and an alignment means is recurrently operable to move the array ofplugs consecutively into alignment with the injectors.
 40. The injectionapparatus of claim 39, wherein the injectors are mounted in parallellinear arrays.
 41. The injection apparatus of claim 39, wherein eachsaid injector comprises a proximal charge collection chamber forreceiving the charge; a propellant port in proximal communication withthe collection chamber for applying propellant to the charge in thecollection chamber in response to operation of the charge propulsionmeans thereby to propel the charge out of the collection chamber; and anozzle in distal communication with the collection chamber and whosedistal tip is, in operation, aligned with a mating one of said bores,for delivery of the propelled charge into the last-mentioned bore. 42.The injection apparatus of claim 41, comprising an array of injectorscoupled to a charge propulsion means and recurrently operable to injectthe charges into the bores of successive set of said plugs, saidpropulsion means having an ON position and an OFF position such that inthe ON position the propellant is delivered from a source of propellantto the injector thereby to propel the charge into the aligned bore, andin the OFF position, the propellant is impeded from delivery from thesource to the injector, said array of injectors mating with the array ofplugs for one-to-one alignment of the injectors with the plugs.
 43. Theinjection apparatus as claimed in claim 42 wherein the propellant isair.
 44. The injection apparatus of claim 43 wherein the collectionchamber is dimensioned and configured, and the propellant pressure anddelivery pulse selected so that there is air entrainment into thecharge.
 45. The injection apparatus as claimed in claim 44 comprisingmeans for recurrently pneumatically actuating the injection apparatus.46. The injection apparatus as claimed in claim 44 comprising means forrecurrently hydraulically actuating the injection apparatus.
 47. Theinjection apparatus as claimed in claim 42 wherein the propellant isfluid.
 48. A cavity drilling tool for rotary coupling to a suitableselected drive, having a rotatable drill bit for drilling a bore in aplug, and having means recurrently operable to advance the tool whenrotating into the plug by a predetermined distance thereby to create thebore and recurrently operable to retract the tool from the plugfollowing the creation of the bore.
 49. A cavity drilling apparatuscomprising an array of cavity drilling tools mating with the array ofplugs for one-to-one alignment of the drilling tools with the plugs;each said drilling tool having a rotatable drill bit for drilling a borein the plug and being mounted in the cavity drilling apparatus forrotary coupling to a suitable selected drive for simultaneously rotatingthe rotatable drill bits and means recurrently operable to advance therotating drill bits together into successive sets of said plugs by apredetermined distance thereby to create the bores and recurrentlyoperable to retract the drill bits together from said last-mentionedplugs following the creation of the bores.
 50. The cavity drillingapparatus of claim 49, wherein the array of plugs is a linear array ofequally spaced plugs, drilling tools are mounted in mating lineararrays, and an alignment means is operable to move the array of plugsconsecutively into alignment with the drilling tools.
 51. The cavitydrilling apparatus of claim 49, wherein the drilling tools are mountedin parallel linear arrays.
 52. The cavity drilling apparatus of claim 49for cyclable use to inject a predetermined discrete charge of plantgrowth modulator into each plug in a succession of plugs arranged insets of plugs, each said set being arranged as a predetermined array ofplugs, comprising an array of cavity drilling tools mating with thearray of plugs for one-to-one alignment of the drilling tools with theplugs; each said drilling tool having a rotatable drill bit for drillinga bore in the plug and being mounted in the cavity drilling apparatusfor rotary coupling to a suitable selected drive for simultaneouslyrotating the rotatable drill bits; and means operable to advance therotating drill bits together into the plug by a predetermined distancethereby to create the bores and operable to retract the drill bitstogether from the plug following the creation of the bores.
 53. Thecavity tool of claim 48, wherein the drill bit has a wide body, a narrowdistal tip and a shoulder between the body and the tip.
 54. The cavitytool of claim 53 wherein the drill bit is symmetrical about its axis ofrotation.
 55. The cavity tool of claim 54 wherein the drill bit is madeof material selected to promote flexing and bending of the drill bit inuse.
 56. The drill/injector combination of claim 16, wherein the meansfor releasably coupling the restraint means to the alignment meansoperates in synchrony with the cyclic drilling and injection steps. 57.The drill/injector combination of claim 20, wherein the actuatoroperates in synchrony with the cyclic drilling and injection steps torecurrently urge the dividers between the OPEN and CLOSED position. 58.A drill/injector combination for cyclable use to inject a predetermineddiscrete charge of plant growth modulator into each plug in a successionof plugs arranged in sets of plugs, each said set being arranged as apredetermined array of plugs, comprising: cavity drilling apparatuscomprising an array of cavity drilling tools mating with the array ofplugs for one-to-one alignment of the drilling tools with the plugs;each said drilling tool having a rotatable drill bit for drilling a borein the plug and being mounted in the cavity drilling apparatus forrotary coupling to a suitable selected drive for simultaneously rotatingthe rotatable drill bits; a charge propulsion means for propelling thecharges into the bores; injection apparatus comprising an array ofinjectors coupled to the charge propulsion means; said propulsion meanshaving an ON position and an OFF position such that in the ON positionthe propellant is delivered from a source of propellant to the injectorthereby to propel the charge into the aligned bore, and in the OFFposition, the propellant is impeded from delivery from the source to theinjector, said array of injectors mating with the array of plugs forone-to-one alignment of the injectors with the plugs; metering apparatuscoupled to the injection apparatus, for one-to-one alignment with theinjectors, comprised of a metering roller, a perforation cover and acoupling means, said metering roller being rotatably attached to theperforation cover and being connectible to a suitable drive, saidmetering roller having peripherally located pockets of a defined volumeto collect the plant growth modulator in a first position, dispense thepredetermined amount of plant growth modulator into the collectionchamber and recharge when returned to the first position; a restraintmeans for receiving and releasably restraining a block of plugs and ameans for releasably coupling said restraint means to an alignmentmeans; a seedling holder for supporting a set plants contained in anarray of plugs, said seedling holder having a series of guides spaced toreceive the set of plants and means to releasably couple the seedlingholder to the restraint means; a bore closing apparatus comprising anarray of bore closing tools mating with the array of plugs forone-to-one alignment of the bore closing tools with the plugs; each saidbore closing tool having a rotatable bore closer for closing a bore inthe plug and being mounted in the bore closing apparatus for rotarycoupling to a suitable selected drive for simultaneously rotating therotatable bore closers; alignment means for successively aligning theplugs with the drill bits, the injectors and the bore closers; andrepositioning means, operable to move the array of plugs consecutivelyinto alignment first with the drill bits, then with the injectors andthen with the bore closers, such that an array of plugs is beingdrilled, while the adjacent drilled array of plugs is being injected andthe injected array of plugs is being closed.
 59. The drill/injectorcombination of claim 58, further comprising control means connected toand operable to recurrently actuate the charge propulsion means and themetering apparatus in synchronism; whereby after each delivery ofpropellant by the propulsion means to the injectors, a remetered chargeis dispensed from the metering apparatus to each of the injectors.